Single step process for producing alkylolated acrylamide-containing interpolymers

ABSTRACT

Heat-hardenable resinous alkylolated unsaturated amide-containing copolymers are made by forming an organic solvent solution containing a mixture of monoethylenic monomers including a vinylidenic amide, an aldehyde or an aldehyde precursor, a free-radical polymerization catalyst and at least 0.1%, based on the total weight of monomers, of an alkaline catalyst, and maintaining the solution at elevated temperature to cause polymerization and simultaneous reaction of amido hydrogen atoms with the aldehyde modifying agent. Etherification of the product may be effected by including a C1-C8 alcohol in the reaction mixture. Amide monomers specified are acrylamide, methacrylamide and itaconic diamide. As comonomers for use with the amides there may be used styrene, alkyl styrenes, halostyrenes, methyl methacrylate, alkyl acrylates, maleic acid and its anhydride and esters and butene-2.  Aldehydes and precursors thereof specified are formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, furfural, paraformaldehyde, trioxymethylene and hexamethylenetetramine. Polymerization catalysts specified are organic peroxides, hydroperoxides and peresters, and azodiisobutyronitrile.  The resulting copolymer solutions are used in coating surfaces, for which purpose they may be combined with solvent-soluble heat-hardenable condensates of formaldehyde with urea, melamine, or benzoguanamine, polyepoxides, e.g. the diglycidyl ether of 2,21-bis-(p-hydroxyphenyl propane), and alkyd resins, e.g. a condensation product of dehydrated castor oil, phthalic anhydride, benzoic acid and glycerine, or the product obtained by copolymerizing a mixture of methyl methacrylate and styrene with a condensation product of dehydrated castor oil, glycerine and phthalic anhydride. Titanium dioxide pigment may be added to the coating compositions. The examples describe the preparation of amide copolymers, using the following ingredients:  (a) monomers:  acrylamide, styrene and ethyl acrylate, with one or more of vinyl stearate, methyl acrylate and butyl acrylate as optional comonomers, (b) aldehyde: formaldehyde, (c) polymerization catalyst:  a mixture of di-tert.-butyl peroxide and azobisisobutyronitrile, (d) etherifying alcohol:  n-butanol, (e) alkaline catalysts: triethylamine or ammonium hydroxide, (f) other ingredients: xylol and ethylene glycol monobutyl ether as solvents, and tert.-dodecyl mercaptan.  In the processes described the various ingredients are added gradually to the reaction vessel as polymerization proceeds.ALSO:Steel panels, either bare or pre-treated, are coated by applying thereto a composition made by the organic solvent solution polymerization of a mixture of monoethylenic monomers including a vinylidenic amide, an aldehyde or aldehyde precursor and optionally, an alcohol, to produce a copolymer containing alkylol or alkoxyalkyl groups in place of amido hydrogen atoms. After application, the coating is hardened by heating at 250-350  DEG F.  Also present in the coating compositions may be aminoplasts, e.g. condensates of formaldehyde with urea, melamine or benzoguanamine, alkyd resins, e.g. a condensation product of dehydrated castor oil, phthalic anhydride and glycerine, and the copolymerization product thereof with a mixture of methyl methacrylate and styrene, and polyepoxides.  The compositions may also contain titanium dioxide as a pigment.  The examples describe the use of coating compositions derived from formaldehyde-butanol modified copolymers of acrylamide, styrene and ethyl acrylate, containing, optionally, one or more of methyl acrylate, butyl acrylate and vinyl stearate as comonomers.

Un d SW Pets monomer addition. The invention includes as an important optional feature, the simultaneous and controlled etherification of the alkylolated interpolymer.

Alkylolated acrylamide-contairiing interpolymers and etherified derivatives thereof are known products. However, production of these products in the past has required the use of a plurality of successive reactions, substantially adding to the cost of production. Thus,xprevious efforts have involved a preliminary polymerization,

and, then, in subsequent steps, the acrylamide-containing interpolymer is alkylolated and etherified.

Referring specifically to the prior art as presented in United States Patent Nos. 2,870,117, 2,940,943, 2,940,944

and 2,940,945, the known procedure requires the following ps:

(1) The charging of all monomers, bptanol, and cata lyst into the reactor. q

(2) Polymerization with free radical catalysts.

(3) Addition of alcoholic formaldehyde and acid catalyst. i

(4) Condensation of acrylarnide and formaldehyde by i refluxing.

(5' Distillation of half of the solvent, in order to replace butanol with xylol or any other aromatic hydrocarbon' solvent. (This step isdetrimental for it eliminates control" of the amount of waterremoval and, as a result, control of the extent of etherification.)

(6) Recovery of the used solvent.

This procedure is not Well adapted to large scale production due to extreme exothermic reaction'of the monomers and difiicult control of processing conditions, which result in poor batch to batch reproduction of results. Control of the degree of etherification is also very difiicult in the known procedure.

In accordance-with the present invention, organic solvent, aldehyde and .the desired monomers including an acrylamide are reacted Withone another in the presence of heat and in the presence of a basic catalyst and a free radical generating polymerization catalyst, and polymerization and alkylolation take place simultaneously. Preferably, the monomers .are added to the organic solvent solution which is added slowly and at a uniform rate (desirably by continuous addition) to permit more precise control of the reaction and to provide a more uniform interpolymer product. Also continuous monomer addition enables temperature control during the reaction despite the highly exothermic reaction which normally occurs. In the presence of alcohol, continuous removal of water, as by refluxing coupled with azeotropic distillation, etherification takesplace at the same time and at least 3,163,623 Patented Dec. 29, 19 64 some of the methylol groups in the alkylolated product are etherified.

The alkaline catalyst is essential to the invention, for its absence leads to the production of an insoluble gelled structure which is not useful.

At least 0.1% of alkaline catalyst, based on the weight of monomers being copolymerized, is essential to avoid gelation. On the other hand, it is preferred to use not more than 1.0% of alkaline catalyst because the products so-produced have slow curing properties and are less desirable Any alkaline compound may be used, those having a nitrogen base being preferred. Amines, and especially tertiary amines are particularly preferred. Thus, inorganic alkaline compounds such as alkali metal hydroxides and alkaline earth metal hydroxides are broadly operable, but are not preferred because these introduce impurities into the resinous product. Ammonia is quite suitable as 'are' quaternary ammonium compounds such as tetramethyl" ammonium hydroxides. Amines such as ethyl amine and butyl amine may be used. However, tertiary amines illustrated by triethyl amine, tripropyl amine and tributyl amine are particularly preferred. The degree of etherification may be changed, and thereby controlled, by changing the amount of alkaline catalyst which is employed.

The present invention includes the presence of acids in the basic reaction medium for this causes the production of catalytic salts which increases the efiiciency of cure. Maleic acid is particularly preferred as the acid for use in forming catalytic salts in situ.

The etherified alkylolated acrylamide-containing interpolymers which may be produced are generally, though not specifically, described, for example, in United States Patent Nos. 2,173,005, 2,870,116, 2,870,117, 2,940,943, 2,940,944 and 2,940,945. Thus, the invention is generally directed to resinous materials obtained by reacting a monoaldehyde, particularly formaldehyde, with an interpolymer of ethylenically unsaturated amide, such as acrylarnide, and one'or more polymerizable ethylenically u'nsaturated monomers. The'se aldehyde modified amide interpolymers may be used as such or etherified by reaction with lower alkyl alcohol. In brief summary, the invention is concerned with interpolymers of an acrylamide withat least'one other ethylenically unsaturated monomer (preferably a monomer containing the group), said interpolymer having replaced by the structure amido hydrogen atoms 3 weight, with unsaturated monomers containing the CH =C group, the invention is not limited to acrylamide or to the presence of a terminal methylene group. Thus, other acrylamide monomers such as methacrylamide and itaconate diamide may be used. While the preferred unsaturated monomers interpolymerized with acrylamide do contain the CH =C group and it is preferred to use combinations of the monomers which form hard polymers such as styrene, vinyl toluene and methyl methacrylate with monomers which form soft polymers such as monoethylenically unsaturated carboxylicacid esters having a terminal aliphatic hydrocarbon group containing from 2-20 carbon atoms, illustrated-by ethyl acrycontaining up to 8 carbon atoms, especially butanol, are preferred for etherification and the etherification reaction a may be carried out up to 100% of the alkylol radical late, butyl acrylate, Z-ethylhexyl acrylate, and stearyl acrylate, the invention is not restricted to the selection of monomers containing the CH =C group or to the selection of preferred combinations of monomers. Thus, monomers which do not contain the CH =C group may be interpolymerized with acrylamide either alone or in the presence of monomers which do contain the CH =C group. Particular attention is directed to maleic acid or anhydride, maleic acid monoesters and diesters, butene-2 and fatty acids containing conjugated unsaturation such as dehydrated castor' oil fatty acids which are useful in the production of interpolymers with acrylamide. Such interpolymers are illustrated by: a solution copolymer of 20 parts of acrylamide, 40 parts of maleic anhydride and 40 parts of butene-2; and by a solution copolymer of 20 parts of acrylamide, 20 parts of maleie anhydride, 20 parts of dibutyl maleate and 40 parts of butene-2.

The interpolymers of the invention result from a solution copolymerization in the presence of free-radical polymerization catalyst. Mercaptan chain terminating agents may, optionally, be present.

Any free-radical generating polymerization catalyst may be used, the selection of catalyst being determined by the desired temperature of the polymerization'reaction. The important point is that the agent liberate free radicals under the conditions of polymerization so that the addition polymerization is facilitated.

Thus, copolymerization catalysts which generate free radicals starting at low temperatures, e.g., from 30-50 C. are usable, these being illustrated by acetyl benzoyl peroxide, peracetic acid, hydroxybutyl peroxide, isopropyl percarbonate, cyclohexanone peroxide, cyclohexyl peroxide, 2,4-dichlorobenzoyl peroxide, and cumene hydroperoxide.

Suitable catalysts which are active to begin generating free radicals at somewhat more elevated temperatures of about 60 C. are illustrated by t-butyl hydroperoxide, methyl amyl ketone peroxide, acetyl hydroperoxide, lauroyl peroxide, methyl cyclohexyl hydroperoxide, tbutyl permaleic acid, t-butyl perbenzoate, di-t-butyl diperphthalate, N,N'-azodiisobutyronitrile and benzoyl peroxide.

Preferably, free-radical generating catalysts which become active at still more elevated temperatures of about 100 C. are used in accordance with the invention, these being illustrated by t-butyl perphthalic acid, p-chlorobenzoyl peroxide, t-butyl peracetate, dibenzal diperoxide and di-t-butyl peroxide.

The aldehyde modifying agent is desirably used in an amount of from 0.2-5 equivalents of aldehyde, and preferably in an amount of from 1-4 equivalents of aldehyde for each amide group used in the formation of the acrylamide interpolymer. The preferred aldehyde is formaldehyde. Othermonoaldehydes, including acetaldehyde, propionaldehyde, butyraldehyde, and furfural, or substances yielding an aldehyde, such as paraformaldehyde, hexamethylenetetramine or trioxymethylenej can also be used.

Etherification of the aldehyde-modified amide interpolymer is preferred, but not essential. Lower alcohols present in the interpolymer although partial etherification is preferred. The degree of etherification is easily controlled in accordance with the invention by adjusting the proportion of alkaline catalyst, such control being a feature of the invention. When less than 100% etherification is effected, the product is a mixture in which the amide hydrogen atoms in some of the acrylamide interpolymer molecules are replaced by the structure ROH. and the amide hydrogen atoms in other of the acrylamide interpolymer molecules are replaced by the structure ROR R representing a saturated aliphatic hydrocarbon radical introduced by the aldehyde modifying agent and R is the residue of the etherifying alcohol.

The alkylolated acrylamide-containing interpolymers of the invention are broadly similar to prior materials in that they may be combined with alkyd resins, epoxy resins and aminoplast resins, etc. However, the products of the invention are specifically and importantly ditferent from prior materials because they exhibit improved compatibility with other resinous materials in organic solvent solution. This improved compatibility is particularly evident in combination with arninoplast resins such as solvent-soluble, heat-hardening condensation products of formaldehyde with polyamines such as urea and melamine. Thus, compatibilty in solution is restricted for melamine resins to about 15% based on the total weight of resin while, the invention permits compatibility at higher concentrations, e.g., up to about by weight.

The invention is illustrated in the examples which follow:

EXAMPLE 1 Charge 333 grams of xylol, 333 grams of butanol and grams of 40% formaldehyde solution in butanol into a reactor equipped with an agitator, condenser, Dean-Stark trap, thermometer and nitrogen inlet.

The initial charge is heatedto reflux temperature Then dissolve grams of acrylamide in 320 grams of butyl Cellosolve and 200 grams of 40% formaldehyde solution in butanol and premix with 400 grams of styrene, 50 grams of methyl acrylate, 150 grams 'of ethyl acrylate and 50 grams of vinyl stearate.

245-255 F. while concomitantly removing water by' azeotropic distillation.

Evaluation of the Interpolymer of Example 1 A white enamel having a composition or 29% titanium dioxide 'riitil, am 33% non-volatile resin, was applied on Bonderi'te' 'S'tel panel using 3 wet film draw downs and baked for 20 minutes 'at 325 F. in a gas fired oven.

The renewing results were dbt'ai'rid:

Pencil Flexibility Toluol Additive Hardness (Conical Resistance Mandrel) 1 None H Passes Fair-good. 0.5% H PO4Acid 211 do Excellent. 0.5% H PQiAdd Resin- 2 do Do.

ous polyol (1).

Note (1): A copolymer of styrene and allyl alcohol having an average molecular, weight @1150 an average equivalent weight, based on hydroxyl functionality, of 222.

EXAMPLE 2 I Example 1 is repeatetl'with "the single exception being the fact that 3.2 :grams of triethyl amine is not included in the monomer blend. g

After 2 /2 hour's, when'15'00 grams of themonomer blend :had been added to the reactor, the {polymer-was gelled and is not soluble in commonorganic solvents.

EXAMPLE '3 This interpolymer is prepared the presence of ammonium hydroxide catalyst. The same procedure used in Example 1 is usedin the :present example.

Composition Charge Grams Acrylamide 150 styrene 40o Ethyl acryl'ate 300 'Viny1stear'ate -100 Methyl acrylate 50 40% solution of formaldehyde in butanol 275 Xylol 233 n-Butanol k 433 Butyl-Cellosolve V. 320 Ammonium hydroxide (28%) 8 di-Tert-butyl peroxide Azobisbutylronitrile 5 Tert-dodecyl mercaptan 14 The interpolyr'nerhad the following physical characteristics: p

(percent) .i.. Viscosity (Gardner) U EXAMPLE 4 Charge Composition Grams 1Acrylami'de 150 Styrene a 400 Methyl acrylate r 50 Ethyl acrylate I 350 Vinyl stearate 4. V 50 Xylol i 333. n-Butanol a 333 'Butyl Cellosolve 320 Grams 40% solution of formaldehyde in butanol 275 Triethyl amine 3.2 di-Tert-butyl peroxide 5 Azobisbutyronitrile 5 Tert-dodecyl mercaptan 14 Procedure for Polymerization Charge 333 grams of xylol, 333 grains of butanol and 75 grams of 40% formaldehyde solution in butanol into a reactor equipped with an agitator, condenser, Dean- Stark trap, thermometer and nitrogen inlet.

The initial charge is heated to reflux temperature (235- 240 R). Then dissolve 150 grams of acrylamide in 320 grams of butyl Cellosolve and 200 grams of 40% for'maL dehyde solution in butanol and premix with 400 grams of styrene, grams of methyl acrylate, 350 grams of ethyl acrylate and 50 gramsof vinyl stearate. I

To this monomer blend add 5 grams of di-tert-butyl peroxide, 5 grams of azobisbur foaitfile, 14 grams of tertiary dode'cyl merc'aptan and 3.2 grams of triethyl amine to provide the desired catalysts.

The above blend is added to the reactor over a 2 /2 hour period of time and the mixture is maintained at 245-25 5 F. while concomitantly removing Water by azeotropic distillation.

The reaction mixture is maintained at reflux temperature (255 F.) for 10 hours. 22 grams of water are collected in the Dean stark trap.

The resulting interpolym'er has the following physical characteristics:

Solids (percent) 47.5

Viscosity (Gardner) W-X The resin of Example4 is utilized in an enamel formulation containing 28% titanium dioxide and 32% nonvolatile resin. v

The characteristics of the enamel are checked without catalyst, with 0.5% phosphoric acid (based on resin solids), and 5% of resinous polyol (based on resin solids). The enamel was draw'n down on Bonderite Steel panel and baked 20 minutes at 325 F.

0.3% Phos- I 0.5% Phosphoric Acid, N0 Addltive phoric Acid 5% Resinous Polyol (see Note 1, Ex. 1)

Gloss and appearance. Excellent. Excellent Excellent. Peneil Hardness uu HB ;l 3 Flemming) (conical Fail bend- Pass bend Pass bend. man re Impact (Forward). Pass 25 in lbs Pefisjs 35-40 in Peas 35-40 in Y s. s.

The above white enamel is also evaluated as a coating applied to aluminum using #40 W. rod drawdown and a baking schedule of 1 minute at 500 F. The following results are obtained.

66.7 parts of a 60% resin solids solution of benzoguanamine-formaldehyde resin in a 50/50 weight ratio mixture of butanol/xylol is mixed with 126 parts of the 47.5% resin solids solution produced in Example 4 and the mixture is pigmented to include 28% by weight of titanium dioxide rutile, based on total solids, and thinned to 32% non-volatile resin solids with xylol. The benzoguanamine-formaldehyde resin is a condensation product of 4 mols of formaldehyde with 1 mol of benzoguanamine in the presence of excess butanol and an acid catalyst to provide a heat-hardening resin etherified with butanol to provide solvent solubility. The benzoguanarnine-formaldehyde resin solution has a viscosity on the Gardner- Holdt scale at 25 C. of G-K.

A 0.003" drawdown of the enamel is made on bare steel panels and baked 20 minutes at 350 F. The following results were obtained:

A heat-hardening solvent-soluble melamine-formaldehyde condensate etherified with butanol to provide solvent solubility is employed in the form of a 55% by weight resin solids solution containing 25% of butanol and 20% of xylol. The melamine-formaldehyde resin is provided by heat reacting 5.5 mols of formaldehyde with 1 mol of melamine in the presence of excess butanol and a small amount of an acid catalyst. The resin solution has a Gardner-Holdt viscosity at 25 C. of L-O and tolerates 180 pounds of mineral spirits per 100 pounds of resin solution. This melamine resin solution is mixed with the resin solution produced in Example 4 to provide a 75/25 weight ratio mixture of acrylamide interpolymer solids and melamine resin solids. The resulting mixture was then milled with titanium dioxide rutile and thinned with xylol to provide a coating composition containing 28% by weight of titanium dioxide based on total solids and 32% by weight of non-volatile resin solids based on the total weight of the solution.

This coating composition is applied to bare steel to form a 0.003 wet film drawdown and baked for 20 minutes at 350 F. The resulting coated product shows good gloss and appearance, a pencil hardness of 3H, very good flexibility and excellent resistance to toluol.

Good results are also obtained by modifying the coating composition of the present example through replacement of the melamine-formaldehyde resin with a corresponding weight proportion of other resins such as:

(l) A castor oil-modified heat-hardening alkyd resin prepared from 33.8 parts of dehydrated castor oil, 39.0 parts of phthalic anhydride, 1.7 parts of benzoic acid and 25.5 parts of glycerine, the oil-modified alkyd product having a solids content of 50% by weight in xylol, a viscosity of Z-Z on the Gardner-Holdt scale, and an acid value of 6;

(2) A copolymer of alkyd resin modified with dehydrated castor oil, the alkyd being prepared from 42.0 parts of dehydrated castor oil, 10.0 parts of glycerine, and 18.0 parts of phthalic anhydride. This oil-modified alkyd is then copolymerized with 27.0 parts of methyl methacrylate and 3.0 parts of styrene to provide a 60% resin solids solution of copolymer in xylene having a Gardner- Holdt viscosity of U-V and an acid value of 8.0; and

(3) A substantially diglycidyl ether of 2,2'-bis-(p-hydroxyphenylpropane) having a molecular weight of about 1000, an epoxide equivalent weight of about 500 (grams per epoxide equivalent weight), and a melting point of from 65-75 C.

8 EXAMPLE 7 A further illustrative butylated methylolated acrylamide-containing interpolymer is produced using the process set forth in Example 4 from the following components:

Charge Composition .Grams Acrylamide 150 Vinyl stearate Styrene 400 Methyl acrylate 50 Ethyl acrylate 350 Butyl acrylate Xylol 333 n-Butanol "l 333 40% solution of formaldehyde in butanol 27S di-Tert-butyl peroxide 5 Triethyl amine 4.2 Azobisbutylronitrile -5 Tert-dodecyl mercaptan 14 The resin product has the following final characteristics:

Solids (percent) 47.1 Viscosity (Gardner-Holdt) U-V EXAMPLE 8 An enamel is prepared using the 47.1% resin solids solution of Example 7 and the 60% resin solids solution of benzoguanamine-formaldehyde resin described in Example 5. These resin solutions are mixed together to provide a weight ratio mixture of 45 parts of the product of Example 7 to 55 parts of benzoguanamine-formaldehyde resin, diluted with xylol and pigmented to contain 28% by weight of titanium dioxide rutile. Dilution is suflicient to provide a non-volaiile resin solids content of 32%.

A 0.003" draw down of the enamel is made on bare steel panels and baked for 20 minutes at 350 F. The following results are obtained.

Gloss and appearance Excellent Pencil hardness 4H-5H Mar resistance Very 'good Toluol resistance Excellent EXAMPLE 9 An enamel is prepared using the 47.1% resin solids solution of Example 7 and a 60% resin solids solution of urea-formaldehyde resin in a solvent medium containing a 20/30 weight ratio of butanol and xylol. This resin solution has a Gardner-Holdt viscosity of L-Q, a capacity 'to tolerate at least 50 pounds of mineral spirits per 100 pounds of resin solution and an acid number of 3-8. These resin solutions are mixed together to provide a weight ratio mixture of 60 parts of the product of Example 7 to 40 parts of urea-formaldehyde resin. This mixture is then diluted with xylol to provide a non-volatile resin solids content of 32% and pigmented with with titanium dioxide rutile to provide 28% by weight of pigment base on total solids.

A 0.003" draw down of the enamel is made on bare steel panels and baked for 20 minutes at 350 F. The following results are obtained.

Gloss and appearance Good Pencil hardness 2H-3H Mar resistance Very good Toluol resistance Excellent Flexibility Excellent 9 EXAMPLE 10 Still another illustrative butylated methylolated acrylamide containing interpolymer is producedusing the process set forth in Example 4 from the following components:

Charge Composition s ng the equ pme t sp fi d in Examp ,1, Com ponent A is charged to the reactor and heated to 230 F. Component B is then dissolved in the heated charge in th react r. The materia s isted i Comp n 0 a e then premixed and added to the reactor slowly Over a 2 hour p r dithe ont nts of the reactor bei g m i tained .a 240-250" F.

The reaction is continued until 27 grams of water are removed by distillation providing a solution containing 47% by weight of non-volatile resin solids and a viscosity on the .Gardner-Holdt scale of QR, the viscosity being measured 211F259 C. grams .of maleic anhydride are added to this solution and 400 ms. of :butanol are distilled away and replaced with x-yiol. The mixture is then refluxed to distill 06 6 additional grams of water.

Grams Acrylamide 150 Styrene 400 Vinyl stearate 200 Methyl acrylate 50 hylac y te, I m v Y -T". *T-T -1----. n-Butanol M 333 Bu yl C l osolve --,---.-.-..-,-.,-.-e-s--.- r 40% solution of formaldehyde in butanaol 275 di-Tert-butyl peroxide 5 Triethyl m n A v 4.2 Azobisbutyronitrile 5 Tert-dodecyl mercaptan 16 The resin product has the following final characteristics:

Solids (percent) 46 Viscosity (Gardner-Holdt) Q-R EXAMPLE 11 Still another illustrative butylated methylolated acrylamide-containing interpolymer is produced using the process set forth in Example 1 from the following components: V

Charge Composition 7 i Grams Acrylamide 150 Styrene .450 Ethyl acrylate 400 Xylol 233 n-Butanol 433 Butyl Cellosolve 320 40% solution formaldehyde in butanol 275 di-Tert-butyl peroxide 5 Triethyl amine 3.2 Azobisbutyronitrile 5 Tert-dodecyl mercaptan 16 The resin product has the following final characteris tics:

Solids (percent) Viscosity (Gardner-Holdt) EXAMPLE 12 This example demonstrates the formation in situ of triethyl amine salt, whichacts as a catalyst for the cur ing of the interpolyer on baking.

Charge Composition com onnnzr A Grams Butanol 450 40% solution offormaldehydein butanol 285 A COMPONENT B Y Acrylamide 150 Butyl Cellosolve 320 Butanol 200.

COMPONENT C Styrene 400 Methyl acrylate 100 Ethyl acrylate 350 Triethyl amine 6 Azobisbutyronitrile 1Q Benzoyl peroxide 7 3 Tert-dodecyl, mercaptan 17 The product has the following final characteristics! Solids (percent) 48.4 Viscosity (Gardner-Holdt) Q This product requires no additional acid catalyst. Films thereof baked for 20 minutes at 250 F. have excellent solvent resistance due to catalytic action of the salt of triethyl amine and maleic anhydride.

It will be understood that the invention is illustrated, but not limited by the specific examples which have been presented 'hereinbefore. It will also be evident that the products of the invention, while useful in diverse types of heat-hardening resinous compositions are primarily useful in the coatingv art in which event they are applied either alone orv in combination with other resins, desirably from a compatible organic solvent solution. These coating solutions may be pigmented or contain dyes,- flow 7 aliphatic aldehyde, a free-radical generating polymerization catalyst, and at least 0.1% by weight, based on the total weight of monomers being copolymerized, of an alkaline catalyst, and maintaining said solution at elevated temperature to cause polymerization and simultaneous reaction of amido hydrogen atoms with the aldehyde contained in said solution.

2. A method as recited in claim 1 in which said mix- 1 ture of monoethylenically unsaturated monomers includes an acrylamide and at least one other polymerizable unsaturated monomer having a CH =C group.

3. A method as recited in claim 2'in which said mixture of monoethylenically unsaturated monomers includes an acrylamide and a proportion of monomer selected from the group consisting of styrene, C -C alkyland halogen ring-substituted styrene and methyl methaorylate and a proportion of monoethylenioally unsaturated carboxylic ester having a terminal aliphatic hydrocarbon chain of from 2-20 carbon atoms.

4. Amethod as recited in claim 1 in which said alkaline catalyst is a nitrogen base compound present in an amount of from 0.l%-1.0% by weight. g

5. 'A method as recited in claim 4 in which said nitrogen base compound is an ammonium compound.

' 6. A method as recited in claim 4 in which said nitrogen base compound is an amine.

7. A method as recited in claim 6 in which said amine is a tertiary amine. I

8. A method of producing heat-hardenable resinous, etherified alkylolated acrylamide-containing interpolymer comprising forming an organic solvent solution comprissaturated monomers including an acrylamideycompound providing aliphatic aldehyde, a free-radical generating copolymerize'd of an alkaline catalyst, and maintaining said solution at elevated temperature to cause polymerization, simultaneous reaction of amido hydrogen atoms with the aldehydecontained in said solution and at least partial etherification of the alkylol groups produced by reaction with said aldehyde.

9. A method as recited in claim 8 in which said mixture of monoethylenically unsaturated monomers includes an acrylamide and at least one other polymerizable unsaturated monomer having a CH =C group.

10. A method as recited in claim 8 in which said alkaline catalyst is a nitrogen base compound.

11. A method as recited in claim 8 in which said monomers are supplied to said organic solvent slowly and at a uniform rate.

12. A method as recited in claim 8 in which said aldehyde is employed in an amount of from 0.2-5 equivalents of aldehyde for each amide group provided by said acrylamide.

13. A method as recited in claim 12 in which said aldehyde is formaldehyde;

14. A method as recited in claim 8 in which said alcohol is a butanol,

References Cited by the Exan iner UNITED STATES PATENTS 2,173,005 9/39 Strain 260874 2,870,117 1/59 Vogel et al. 26072 2,978,437 4/61 Christensen et al. 26072 3,037,963 6/62 Christenson 26072 LEON I. BERCOVITZ, Primary Examiner.

WILLIAM H. SHORT, DONALD E. CZAJA,

' Examiners. 

1. A METHOD OF PRODUCING HEAT-HARDENABLE RESINOUS, ALKYLOLATED ACRYLAMIDE-CONTAINING INTERPOLYMER COMPRISING FORMING AN ORGANIC SOLVENT SOLUTION COMPRISING A MIXTURE OF POLYMERIZABLE MONOETHYLENICALLY UNSATURATED MONOMERS INCLUDING AN ACRYLAMIDE, A COMPOUND PROVIDING ALIPHATIC ALDEHYDE, A FREE-RADICAL GENERATING POLYMERIZATION CATALYST, AND AT LEAST 0.1% BY WEIGHT, BASED ON THE TOTAL WEIGHT OF MONOMERS BEING COPOLYMERIZED, OF AN ALKALINE CATALYST, AND MAINTAINING SAID SOLUTION AT ELEVATED TEMPERATURE TO CAUSE POLYMERIZATION AND SIMULTANEOUS REACTION OF AMIDO HYDROGEN ATOMS WITH THE ALDEHYDE CONTAINED IN SAID SOLUTION. 